Exodus 28:35-37

35And it shall be on Aaron for service; that his sound may be heard when he goeth into the sanctuary before Jehovah, and when he cometh out, that he may not die.

36And thou shalt make a thin plate of pure gold, and engrave on it, as the engravings of a seal, Holiness to Jehovah!

37And thou shalt put it on a lace of blue, and it shall be upon the turban — upon the front of the turban shall it be.